Long-term observation of real-world road traffic emission factors on a motorway in Switzerland

Abstract. Carbonaceous aerosols have great influence on the air quality, human health and climate change. Except for organic carbon (OC) and elemental carbon (EC), brown carbon (BrC), mainly originates from biomass burning, as a group of OC with strong absorption from the visible to near-ultraviolet wavelengths, makes a considerable contribution to global warming. Large amounts of studies have reported long-term observation of OC and EC concentrations throughout the word, but studies of BrC based on long-term observations are rather limited. In this study, we established a two-wavelength method (658 nm and 405 nm) applied in the Sunset thermo/optical carbon analyzer. Based on one-year observation, we firstly investigated the characteristics, meteorological impact and transport process of OC and EC. Due to BrC absorbs light at 405 nm more effectively than 658 nm, we defined the enhanced concentrations (dEC = EC405 nm−EC658 nm) and gave the possibility to provide an indicator of BrC. The receptor model and MODIS fire information were used to identify the presence of BrC aerosols. Our results showed that the carbonaceous aerosols concentrations were highest in winter and lowest in summer. Traffic emission was an important source of carbonaceous aerosols in Nanjing. Receptor model results showed that strong local emissions were found in OC and EC aerosols, however dEC aerosols were significantly affected by regional or long-range transport. The dEC / OC and OC / EC ratios showed similar diurnal patterns and the dEC / OC increased when the OC / EC ratios increased, indicating strong secondary sources or biomass burning contributions to dEC. Two biomass burning events both in summer and winter were analyzed and the results showed that the dEC concentrations were obvious higher in biomass burning days, however, no similar levels of the OC and EC concentrations were found both in biomass burning days and normal days in summer, suggesting that biomass burning emission made a great contribution to dEC and the sources of OC and EC were more complicated. Large number of open fire counts from the northwest and southwest areas of the study site were monitored in winter, significantly contributed to OC, EC and dEC. In addition, the near-by YRD area was one of the main potential source areas of dEC, suggesting that anthropogenic emissions could also be important sources of dEC. The results proved that dEC can be an indicator of BrC in biomass burning days. Our modified two-wavelength instrument provided more information than traditional single-wavelength thermo/optical carbon analyzer and gave a new idea about the measurement of BrC, the application of dEC data need to be further investigated.

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Identification and quantification of particulate tracers of exhaust and non-exhaust vehicle emissions

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-5187-2019 ◽

2019 ◽

Vol 19 (7) ◽

pp. 5187-5207 ◽

Cited By ~ 14

Author(s):

Aurélie Charron ◽

Lucie Polo-Rehn ◽

Jean-Luc Besombes ◽

Benjamin Golly ◽

Christine Buisson ◽

...

Keyword(s):

Road Traffic ◽

Exhaust Emissions ◽

Emission Factors ◽

Traffic Emissions ◽

Chassis Dynamometer ◽

Traffic Emission ◽

The Road ◽

Light Duty ◽

Key Species ◽

Brake Wear

Abstract. In order to identify and quantify key species associated with non-exhaust emissions and exhaust vehicular emissions, a large comprehensive dataset of particulate species has been obtained thanks to simultaneous near-road and urban background measurements coupled with detailed traffic counts and chassis dynamometer measurements of exhaust emissions of a few in-use vehicles well-represented in the French fleet. Elemental carbon, brake-wear metals (Cu, Fe, Sb, Sn, Mn), n-alkanes (C19-C26), light-molecular-weight polycyclic aromatic hydrocarbons (PAHs; pyrene, fluoranthene, anthracene) and two hopanes (17α21βnorhopane and 17α21βhopane) are strongly associated with the road traffic. Traffic-fleet emission factors have been determined for all of them and are consistent with most recent published equivalent data. When possible, light-duty- and heavy-duty-traffic emission factors are also determined. In the absence of significant non-combustion emissions, light-duty-traffic emissions are in good agreement with emissions from chassis dynamometer measurements. Since recent measurements in Europe including those from this study are consistent, ratios involving copper (Cu∕Fe and Cu∕Sn) could be used as brake-wear emissions tracers as long as brakes with Cu remain in use. Near the Grenoble ring road, where the traffic was largely dominated by diesel vehicles in 2011 (70 %), the OC∕EC ratio estimated for traffic emissions was around 0.4. Although the use of quantitative data for source apportionment studies is not straightforward for the identified organic molecular markers, their presence seems to well-characterize fresh traffic emissions.

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Identification and quantification of particulate tracers of exhaust and non-exhaust vehicle emissions

10.5194/acp-2018-816 ◽

2018 ◽

Cited By ~ 1

Author(s):

Aurélie Charron ◽

Lucie Polo-Rehn ◽

Jean-Luc Besombes ◽

Benjamin Golly ◽

Christine Buisson ◽

...

Keyword(s):

Road Traffic ◽

Exhaust Emissions ◽

Emission Factors ◽

Traffic Emissions ◽

Chassis Dynamometer ◽

Traffic Emission ◽

The Road ◽

Diesel Vehicles ◽

Key Species ◽

Brake Wear

Abstract. In order to identify and quantify key-species associated with non-exhaust emissions and exhaust vehicular emissions a large comprehensive dataset of particulate species has been obtained thanks to simultaneous near-road and urban background measurements coupled with detailed traffic counts and chassis dynamometer measurements of exhaust emissions of a few in-use vehicles well-represented in the French fleet. Elemental Carbon, brake-wear metals (Cu, Fe, Sb, Sn, Mn), n-alkanes (C19–C26), light molecular weight PAHs (Pyrene, Fluoranthene, Anthracene) and two hopanes (17α21βNorhopane and 17α21βhopane) are strongly associated with the road traffic. Traffic-fleet emission factors have been determined for all of them and are consistent with most recent published equivalent data. When possible, light-duty and heavy-duty duty traffic emission factors are also determined. Most of the first ones are in good agreement with emissions from chassis dynamometer measurements in absence of significant non-combustion emissions. This study has shown that ratios involving copper (mainly Cu/Fe and Cu/Sn) could be used to trace brake-wear emissions as they seem to be roughly constant in Europe and as longer as Cu-free brake are not largely spread. In France where the traffic was largely dominated by diesel vehicles in 2011 (70 %), the OC/EC ratio typical of traffic emissions was around 0.44. On the contrary, the use of quantitative data for source apportionment studies is not straightforward for the identified organic molecular markers; while, their presence seems to well-characterized fresh traffic emissions.

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